Patent GB-778082-A (GB)
Title: Improvements in or relating to aircraft trainers
IPC: G09B9/14
Filed: 1954-07-21
Abstract: 778,082. Ground trainers for pilots. LINK AVIATION, Inc. July 21, 1954 [Jan. 29, 1954], No. 21325/54. Class 4. A ground aviation trainer has a simulated cockpit and dummy flight controls, and means under control of the trainee through the dummy flight controls for vibrating the cockpit about its pitch axis to simulate buffeting. In Fig. 1, the fuselage 10 is supported at a universal joint 14 on a pillar 13, and is adjustable in pitch by a hydraulic jack 501 at the rear, and in roll by a jack 502 pivoted to the fuselage in the transverse plane containing the joint 14. Fed to these jacks are signals simulating buffeting of the aircraft when it approaches flight conditions near stall, and signals simulating rough air effects modified in accordance with the computed dynamic pressure. In the dynamic pressure computer, Fig. 3, an alternating voltage of positive reference phase is applied to the potentiometer R301, the characteristic of this being shaped by resistances R302- R305. The wiper arm is positioned in accordance with the simulated altitude, and the resulting signal fed to potentiometer R306, the arm of which is positioned by the simulated true air speed unit, and the signal amplified by U-302, the output of which feeds amplifier U-303 giving a dynamic pressure signal for any other circuit, and feeds a potentiometer R307, the arm of which is positioned by the true airspeed unit, and derives a signal fed to amplifiers U304, U305 and a summing resistor R308 to a servo-amplifier U306 controlling a shaft M-300. This shaft drives a tachometer generator G providing a rate feed back through winding F-300 and resistor R309, and the arm of potentiometer R311 provides a follow up signal through resistor R310. The position of shaft M300 is thus dependent on dynamic pressure. In the rough air computer, Fig. 5, shaft M300 positions the wiper arms of constantly energized potentiometers R501 and R502. The signals from B501 and R502 are modified by potentiometers R503 and R504 adjusted for rough air intensity by the instruct- or, and led through contacts 3 and 4 of a relay K501 which is operated when the instructors rough air switch S501 is on, to the ends of potentiometers R505-R507. The wiper arms of these are positioned by a motor M500 energized when the switch S501 is closed and when a relay indicates that the trainer is " airborne," and driving a transmission 503 of known type converting a unidirectional drive to an irregular bidirectional rotary motion. The signals from the arms of potentiometers R505-R507 are fed to angle of pitch, bank, and roll indicator servoamplifiers U503-U505. The signal applied to resistors R505-R507 is also fed through irregularly closed switches S502, S503 to the indicated air speed servo amplifier U506. A D.C. signal is fed to potentiometers R518, R519 and R520, and R517, R529 and R521 adjusted by the rough air motor M500, and through contacts 5 and 6 of relay K501 to actuate servo amplifiers U501, U502 controlling the valves V501, V502 of the jacks 501, 502 shown in Fig. 1. The piston rods of these jacks adjust the arms of potentiometers R527, R528 to provide follow-up signals fed to the amplifiers U501, U502. In the buffeting computer, Fig. 4, a constant potential is fed to potentiometer R401, the arm of which is adjusted by the simulated wing flaps motor, the resulting signal being fed to a summing amplifier U401, together with a signal derived from R403 proportional to the simulated angle of attack. The resulting sum is further modified by potentiometer R430 adjusted by the simulated true air speed unit, and potentiometer R431 adjusted by the simulated altitude unit, and fed to a summing amplifier U403. The signals from potentiometers R401, R403 are also fed to a summing amplifier U404, together with signals from potentiometer R415 adjusted by the wing flaps motor, and a mach number unit comprising potentiometers R417, R420 adjusted by the true air speed simulator, and potentiometers R418, R421 adjusted by the altitude simulator. The output from amplifier U401 is also applied through amplifier U402 and a contact 3 of relay K401, to amplifier U403. The relay K401 is closed when the trainee opens his airbrakes. The output of amplifier U403 represents a lift coefficient increasing with angle of attack, and its output is applied to one terminal of a transformer T400. The output of the amplifier U404 is applied to the other terminal, and represents a lift coefficient decreasing with angle of attack. The output of transformer T400 is applied to a phase detector U405, so that when stalling conditions are approached and the negative signal from U404 overcomes the positive signal from U403, the detector U405 actuates a relay to operate a buzzer K404, from which a signal is derived and fed through an intensity control R427 to the terminal 520, Fig. 5, to actuate the jacks 501,502 to simulate buffeting.